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Research Nut: Macadamias

High-monounsaturated-fat diets for patients with diabetes mellitus: a meta-analysis.

Garg, A, 1998. High-monounsaturated-fat diets for patients with diabetes mellitus: a meta-analysis. AJCN, 67:577S-582S.

The most recent position statement on nutrition from the American Diabetes Association recommends an individualized approach to nutrition that is based on the nutritional assessment and desired outcomes of each patient and that takes into consideration patient preferences and control of hyperglycemia and dyslipidemia. To achieve these nutritional goals, either low-saturated-fat, high-carbohydrate diets or high- monounsaturated-fat diets can be advised. A meta-analysis of various studies comparing these two approaches to diet therapy in patients with type 2 diabetes revealed that high-monounsaturated-fat diets improve lipoprotein profiles as well as glycemic control. High-monounsaturated- fat diets reduce fasting plasma triacylglycerol and VLDL-cholesterol concentrations by 19% and 22%, respectively, and cause a modest increase in HDL-cholesterol concentrations without adversely affecting LDL-cholesterol concentrations. Furthermore, there is no evidence that high-monounsaturated-fat diets induce weight gain in patients with diabetes mellitus provided that energy intake is controlled. Therefore, a diet rich in cis-monounsaturated fat can be advantageous for both patients with type 1 or type 2 diabetes who are trying to maintain or lose weight.

Effects of a macadamia nut enriched diet on serum lipids and lipoproteins compared to a low fat diet.

Colquhoun, D.M., J.A. Humphries, D. Moores, S.M. Somerset, 1996. Effects of a macadamia nut enriched diet on serum lipids and lipoproteins compared to a low fat diet. Food Australia. 48(5):216-22.

Macadamia nuts are a native Australian food rich in the monounsaturated fats, oleic acid and palmitoleic acid. A monounsaturated fatty acid-rich diet (MD), enriched with macadamia nuts (40% energy as fat, 20% energy from macadamia nuts) was compared with a high-complex-carbohydrate diet (HC) for effects on serum lipid and lipoprotein levels. Subjects (7 female, 7 male) between 25 and 59 years of age were randomly allocated either to MD followed by HC, or vice versa. Each dietary phase lasted 4 weeks. Both diets lowered serum cholesterol by 7.9% (p<0.01) and low density lipoprotein cholesterol (LDL) by 10.7% (p<0.01) compared with baseline values. The MD led to a 20.9% decrease in serum triglyceride levels (p<0.01). Triglyceride levels were not affected by HC. High density lipoprotein cholesterol (HDL) decreased 13.1% with HC (p<0.05). MD and HC were equally effective in lowering serum cholesterol LDL levels, and MD unlike HC lowered triglyceride levels without affecting HDL levels.